Method of making golf balls



Feb. 28, 1950 R. F. SMITH METHOD OF' MAKING GOLF BALLS Filed June 4, 1946 ELS-3 Patented Feb. 28, i950 UNITED STATES PATENT FFICE METHGD OF MAKING GOLF BALLS Robert Fulton Smith, Elyria-,lithim assigner :to The Worthington BallCompany, Elyria, Ghio, a cor-poration yof Ohio Application J une 4, 1946, 'Serial No. 674,321

7 Claims; l

My invention'relates to an improved ,methodfof manufacturing golf balls.

More specifically my invention relates to vthe making of an improved golf ball whereo'fthe Slayer or rubber winding between vthe central core Aand the outercover will 'communicate a 'greaterpressure to said core and cover surfaces than golf balls made according t0 previously` known methods.

Prior to my invention, eiortsv to lincrease the internal pressure exerted radially outwardly against the outwardmost conning ball vvcover have, so far as I am aware, been confined to vsuch expedients as injecting additional :liquid :or `gas into the central core of a fully completed golf ball, usually by means of a hypodermic needle forced successively through the outermost cov-er and intervening rubber winding into the `interior of the core, which core is in the form of-a vhollow rubber sphere.

Golf balls manufactured `according to such prior methods have been found to vary considerably in initial performance 'and with increased variation as actually used, as a result of the injected liquid frequently disturbing the concentrici-ty i of the different portions of the core 'shell andalso asa result of subsequent leakagefoffliquid `through the aperture of its wall caused by the injection :of the needle therethroughp As distinguished from the prior methods, the resiliently eiective internal pressure exerted Iagainst the outer cover of the ball made according to 'my'im-proved method Ais achieved by the Yattempted expansion of the Arubber winding which is interposed between the golf ball core and the outer cover and this I accomplish without requiring `the walls of the core `or the completed ball .to be `punctured or otherwise-disd turbed subsequent to the completion I.of manufacture.

My improved method involves the manufacture of golf balls according -to an improved method wherein the so-called ball center, comprising a central core and a winding. of rubber tape and/ or thread, wound under. tension upon said core, is contracted in diameter by abstraction o'f 'heat from the winding, and while contracted, a -layer of suitable' thermoplastic material, such as gutta percha, balata, or like materials, sometimes including additional materials, is molded onto lthe exterior surfaces of the wall center in the usual way.

An object of my invention is to provide an improved method for making golf balls wherein subsequent to the applicationof the cover `thereto the rubberwinding 'interposed between the core and :the coverv is veiective `to increase `its reiifort to expand. to .a degree greatly beyond the, degree of such effort where golf balls are manufactured according to previously known methods.

`Another object of my. invention is to provide an improvedgolf ball provided with a rubber windfingU interposed between a central core and the outer :confining cover which after the cover `is applied and 'responsive to ambient temperatures will strongly tend to expand andtherebyiexert considerably, increased expansive pressure both against the* outermost cover and inwardly against the. outer surface of the core;

Another :objectzof my invention is to providean improved method .for manufacturing `golf balls characterized by the exposure 'of the wound ball centerfto such :a coolingfmedium as Dry Ice (solidified carbon dioxide gas), or lother material. rev duced to exceedingly low temperature, and placing the cover on the resultently contracted center whilethe contraction of the center is substantially maintained.`

Another object loi" my invention is to provide an improved :golf ball sov constructed, vas to `greatly increase the retractive eort of the rubber windingl which is interposed between the 'golf --ball I'core and the inner surface of the golf ball cover, said increase becoming eiective only after the cover is applied.

Another yobject of lmy, invention is. to leffect economies in the cost of manufacture oli* golfballs which `arise from the lack of necessity of applying the `rubber winding under as great tensionas heretofora-but which after applicationof the cover becomes highly tensed.

Other objects vof my invention vand the invention itself will be better understoodby `reference tothe accompanying specification which rel-artes to aspeciiic embodiment of my invention` and wherein references are had to the accompanying illustrated drawingsindicating the different steps of the process which are susceptible to indicative illustration;

In the drawings,

l is a View of a golf ball center `comprising a central sphericalcore, and a rubber winding applied thereto, the core being illustrated in elevation and the winding being indicated as if in `diametrical cross section.

Fig. v2'is very vsimilar to that of the View of Fig...1. the central core being the same as in Fig'. 1 'but the windings being illustrated as contracted as `a result of heat being abstracted from the center of Fig. 1.

Fig.` 13 illustrates the contracted wound center of Fig. 2 encased in a spherical two-mold cavity, with a layer of thermoplastic cover material interposed between the outermost circumferential surfaces of the center and the inner walls of the cavity and indicating liquid conduits adapted to successively convey cooling, heating, and cooling liquid for subjecting the ball and cover to variations in temperature dura molding process.

Fig. 4 illustrates the resultant covered golf ball.

The golf ball of my invention preferably comprises a central core l, and said core may prefera-bly comprise a thin walled hollow rubber shell which is preferably filled with a substantially incompressible liquid, said liquid being of any suitable composition, and may or may not be subject to expansion or contraction, responsive to changes of temperature.

However, the principles of my invention are well served by making the spherical core l in any suitable size and weight, of any suitable solid material, with or without the use of a liquid filling.

Over the core l, I preferably provide a rubber filling comprising successive superimposed rubber windings, the rst 2, being preferably of a thin rubber tape and wound under tension and over the tape winding 2 I preferably provide a superposed winding 3 of rubber thread also wound under predetermined tension.

Should a lquid-lled core be employed, the core l may, in known manner, be subjected to chilling by abstraction of heat therefrom by placing it in proximity to Dry Ice, whereby the central liquid becomes solidified to afford a solid spherical base, which is-formsustaining during the winding operations, and upon which the rubber winding may be superposed.

The freezing of the central core liquid may be accomplished without substantially aecting the volume of space occupied thereby, it being well known that suitable liquid, which does not appreciably expand or contract when frozen, has commonly been employed for a central core for golf balls.

The wound center, constructed as indicated in Fig. 1, will preferably be of appreciably greater diameter than those previously covered, to adapt it for covering by a confining cover of the same effective thickness, as heretofore employed.

The next step of the process is the subjecting of the entire wound center illustrated in Fig. 1 to the chilling effect of Dry Ice or other freezing medium whereupon the abstraction of heat from the winding or windings 2 and 3 causes the wound center to be appreciably reduced in diameter as roughly indicated in Fig. 2 which shows that, whereas the core retains its original diametrical dimension, the rubber winding is reduced in volumetric content.

Inherently rubber material will contract greatly, when cooled, to a greater degree than any similar material and, since the rubber winding was previously wound under tension, its contraction will not increase the tension of the winding but will decrease said tension, because of the effect of the resulting shorter length of the chilled convolutions.

I have found that the abstraction of heat from the windings which reduces the temperature thereof to approximately 100+ degrees below Fahrenheit zero, is not attended by breakage of the tape or thread winding material, under normal conditions of handling.

With the ball center of Fig. 2 in the contracted state, and of over-al1 reduced diameter, such center is then introduced into a two-part mold cavity, as indicated in Fig. 3, each part of the cavity being provided with a lining comprising a hemispherical balata, gutta percha or equivalent thermoplastic cup.

After insertion of the ball in embraced relation to the balata or like cups, the uppermost part 1 of the mold is clamped down tightly over the ball center and said cover material to securely and confiningly clamp the opposing edges 8 of the hemispherical cups 4 and 6 together, the dimensions of the mold cavity thus substantially perfected by the closing of the mold being so related to the contracted ball of Fig. 2 that the ball center is closely held centered within the balata cups.

The molding of the cover onto the rubber nlling, comprising said core and thread winding, is then achieved in any previously known suitable manner, and by circulation of ice water or other chilled liquid through conduits, such as indicated at 9 and l0, the two mold parts 5 and I are rst chilled.

The pre-chilling of the mold parts avoids unduly rapid abstraction of heat by the mold parts from the winding of the wound center, and the interpositioning of the thermoplastic cups 4 and 6 between the outer surfaces of the filling 3 exercises a sufficient heat insulation effect as to prevent excessive abstraction of heat from said Winding.

According to the prevailing practice a somewhat thin space indicated at Il is provided to receive excess cover material which is squeezed out of the mold cavity during the molding operation. The molding surfaces of the molding dies 5 and 'I are preferably provided with small inwardly directed protuberances I2, which by indenturing, provide the indentations I3, Fig. 4, commonly provided on the outer surfaces of the ball cover.

After closing the mold upon the balata embraced filling center, a source of superheated steam is put in communication with the conduits 9 and I0 and the mold parts are therefore heated to a relatively high temperature preferably above 212 degrees Fahrenheit, 290 degrees being suitable, to thermally cause the previously solid balata or other thermoplastic material of the cups 4 and 6 to become plastic and fluid, whereupon the substantially confined cover material of the cups ows freely around the confronting surfaces of the exterior of the wound center of Fig. 2 and around the dimple projections l2 of the cavity walls and will penetrate between the interstices of the outermost layers of rubber thread 2.

The penetration of ybalata material through the outermost interstices between the different convolutions of rubber thread securely anchors the interior of the golf ball cover to the exterior of the thread winding 3.

After such a period of time as is required to render the balata or like cover material substantially plastic, the flow of superheated steam through conduits 9 and l0 is discontinued and before the molding heat has substantially increased the temperature of the rubber winding, and ice water is again directed through said con` duits to again achieve chilling of the mold to conge'alingly solidify the cover material in superposed relation about the wound center, to permit ready removal of the covered ball from the winding is applied, while tensed iasiclose tothe elastic limit thereof as; ispraQticall-y possible.`

Althoughl the present method.ofl manufacturing golf ballsymay be employedfwhere the Afilling windinglis applied under the maximum possibletension, yet for most purposes, itmaybe more desirable for reasonsof economyl to employlmy method to such a winding applied under tensionv which is safely below the elastic limit ofthe rub-y ber material. The applieationof highly tensed winding is commonly accompanied lby frequent" breaking of the rubber thread and'also commonly, the completel winding ,may involve separate lengths of Winding withthe ultimate result that,

the completed ball will not rsufficiently resist inwardly directed compressive force and mayhave to be junked'or soldratra much loweripricethan a ball having a continuous Winding. could be sold for.

Actually, balls madey according to my improved methodemploy heavier thread, wound' well under the elasticlimit of the rubber material, can be wound withoutl danger-fi of breaking the thread and under: a relativelylower tension `than heretofore employedfor ballsof thev best quality, and by the effectof `the nal, thermalI expansion of thehallI filling itsradial outwardly directed pressure asserted oni-the ball cover,makes such 4a ball resist inwardly: directedcompressive effects.

The heavier rubber thread is` less` expansive, the winding thereof is accomplished with less danger of breaking the thread and theresultant balls are not required to `bejunked or-sold at a lower price,` thereby effecting substantial economies in an article which must be sold in a very highly competitive market.

ll/iyyimproved golf ball may therefore; comprise a more compacted rubber winding'than has heretofore been economically possible and this yfact, coupledywith its uniformly high pressure keffect upon `the cover, achieves a very beneficial effect on the ball whenused.`

Whereas l have. stated my preference that the initially Wound center should have a diameter greater than its ultimate diameter, and whereas this statement comprehends winding the center to a greater diameter than centers have previously been wound for inclusionin` a cover having the same thickness, yet at the same time this does not preclude the winding of'my-center -to the same diameter as previously commonly employed, and

then thermally contracting the winding so that a thicker cover may be` used to afford greater durability, the outside diameter of the ball being, of course, required to be the standard diameter in both cases.

It will be understood that the present inven-v tion relating to contracting the rubber filling to 2--3 and in some cases including the core i by chilling it to extremely low. `temperature and applying the cover over the contracted rubber filling, is applicable to balls employing other filling materials than rubber, and which are similarly thermally contractable to a marked degree and I therefore, for the purpose of this application and,` the claims: thereof; dene the term' rubberv as comprising all substitute materials which mayv be employedforsaid ,nlling which contract, when chilled and subsequentlyxpand responsive to y diametrically too, large to be contained in a normal sized cover by exposure of saidcenter to a medium such as,.DryIce,.to effectthermoontraction of the winding tov reduce its` outside diametenthen connningthe chilledV reduced center in a lsplierical mold cavity with a layer of suitable thermoplastic golf ball cover material substantially liningl the walls of thev spherical cavity, thecavity being. of such diameter relative to the thickness, of said lining and the contracted volume of said centenas to exert confining pressure upon the outer surface ofisaid: lining and center, then yso rapidly heating the mold cavity for such a limited period of time as to exteriorlyv apply sufficient heat-to the cover material as to plasticize the same tor permit.; portions of said material to enter interstices between the outermost convolutions of` said center winding before the temperatureof the winding material has become so increased as to effect substantial thermal l expansion of said material, and thereafter abstracting heat from themold cavity by chilling the mold cavity walls to congealingly solidify said coverl material then removing thecovered center from said cavity for exposure to normal atmospheric temperatures.

2. The method of'making gOlf balls consisting of the applicationof a tensed rubberA winding overa central core until .the diameterfof the woundcenter is substantially greater than its desired ultimate diameter, then extracting heat from the wound` center by exposure thereof to a freezing medium which has been reduced to an exceedingly low temperature to effectr thermal contraction of said Winding to substantially decreaseyits diameter, and then compressivelypconlining the chilled contracted 'wound center in a spherical. mold cavity with a layer of suitable thermoplastic golf ball cover material interposed between the surface of said center and the walls of the cavity, then before the temperature of said winding has increased suflicientlyto eifect substantial thermal-expansion thereof, heating the mold cavity` to apply plasticizing heat to thecover material forA `an insuflicient length of time to cause `the molding heat .to` substantially permeate the chilled wound center, and then abstracting heat from the mold cavity to congealablf,7 solidify said cover in relative anchored relation `to the outermost convolutions of said winding, and then. removing the covered center from said cavity for subsequent exposure to ambient normal atmospheric temperatures.

3.' The methodof making golf balls consisting of providing a core by enclosing a noncompress- Y ible liquid in a spherical rubber envelope, ab-

rubber winding, under tension onto said core, said core to provide a substantially spherical golf ball center, then abstracting heat from the winding by exposure thereof to an externally located exceedingly low temperature freezing medium such as Dry Ice for a sufficient period of time as -to effect thermal contraction of said winding to substantially decrease its diameter, then closely confining the wound center, before it has reabsorbed suicient heat as to substantially reexpand it, in a spherical mold cavity with a layer of suitable thermoplastic substantially tough golf ball cover material which is much less elastic than the winding rubber interposed between the surface of said center and the walls of the cavity, heating the walls of the mold cavity to communicate plasticizing heat to the cover material, and after said cover material is sufficiently fluent to cause portions thereof to enter the interstices of the outer convolutions of the contracted winding, and before said Winding has been heated sufliciently to cause it to be substantially thermally expanded, abstracting heat from the mold cavity to congealingly solidify said material, with portions of said material disposed in relatively anchored relation to said outermost convolutions of the winding, whereby upon removing the golf ball from the mold for exposure to ordinary ambient atmospheric temperatures the cover will gradually be super-tensed, by the effect of attempted diametrical thermally effected expansion of the rubber material of said center.

4. The method of making golf balls consisting of the application of a tensed rubber winding over a central core until the diameter of the wound center is substantially greater than its desired ultimate diameter, then abstracting heat from the winding by exposure thereof to an exceedingly low temperature freezing medium to effect thermal contraction of said winding to decrease its volume, then while so contracted closely confining the contracted wound center in a spherical cavity of an unheated mold with a layer of suitable thermoplastic tough and iiexible golf ball cover material which is substantially much less elastic than said winding material, interposed between the outer surface of said winding and the walls of the cavity and heating the walls of the mold cavity to communicate plasticizing heat to the cover material, before said winding has absorbed suicient heat to substantially expand it, and when said cover material is sufficiently fluent to cause portions thereof to enter the interstices of the outer convolutions of the contracted winding and before any except the outer convolutions of said winding have substantially increased its temperature, rapidly abstracting heat from the mold cavity to congealingly solidify said cover in relatively anchored relation to said outer convolutions, whereby upon removing the golf ball from the mold for exposure to ordinary ambient atmospheric temperatures increased tensing of the cover is achieved to a substantial degree, as a result of consequent attempted diametrical expansion of the windings and the inherent inability of the material of the confining cover to stretch to an appreciable degree.

5. The method of making golf balls of the general type which comprises an outer confining cover of balata, gutta percha, or equivalent golf ball cover material which is tough, exible and of low elasticity as compared to rubber and a iilling of which at least a substantial portionis composed of highly resilient rubber connedly disposed within the cover and having the outer surface of said filling interlocked with the inner surface of the cover, comprising rst, imparting to a body of said lling material a spherical form with a substantially rough outer surface, then abstracting heat from the lling to reduce its temperature to an exceedingly low temperature to effect volumetric contraction of said lling, then while said filling is of reduced diameter effected by its said contraction, molding a layer of said cover material directly on to the said outer surface of said filling in a spherical confining mold cavity, then quickly abstracting heat from the cover, and removing the covered filling from said cavity, whereby upon exposing the covered golf ball to ambient atmospheric temperatures, said filling will thermally expand and will impart substantially increased circumferential-tension creating force to said cover.

G. The method of manufacturing golf balls characterized by the exposure of the ballcenter comprising a winding of tightly elastic rubber strand material, to such a cooling medium as Dry Ice, to reduce the temperature of said Winding to an exceedingly low temperature approaching the temperature of said cooling medium to effect a thermal diametrical contraction thereof, and then, before said winding has substantially increased its average temperature, closely molding a cover comprising a substantially large portion of thermoplastic flexible and tough material which is of much less elasticity than the material of said winding on the contracted wound center, whereby upon subsequently exposing the covered ball to ambient atmospheric temperature condi-tions, the winding thereof will expand to substantially increase the tension of the cover.

7. The method of making golf balls, comprising the making of a spherical ball center by applying a rubber winding under tension over a central'core, substantially contracting the diameter of the center by abstraction of heat therefrom, confining the contracted center closely and compressively within a mold cavity having a lining of thermoplastic ball-cover material which is of low elasticity as compared to rubber and is substantially tougher than rubber, heating the cavity walls while said material is compressed between said center and the cavity walls to plasticize the material, and then chilling the cavity walls to solidify the cover material, whereby the center is closely confined within the cover, then exposing said covered ball to temperatures equal to any ambient atmospheric temperature.

' ROBERT FULTON SMITH.

REFERENCES CITED The following references are of record in the rile of this patent:

UNITED STATES PATENTS Number Name Date 1,482 185 Egerton Jan. 29, 1924 1,534,104 Gammeter Apr. 21, 1925 2,264,604 Young Dec. 2, 1941 2,278,381 Reichard Mar. 31, 1942 2,314,964' Young Mar. 30, l1943 

